[FIX] SQL query results in invalid reference

With post-migrate.py in mrp module there is a query, which uses aliased table without setting this alias. This commit will fix this.
[FIX] don't expect key 'host' to exist
Merge pull request #110 from hbrunn/8.0-migrate.py-conn_params

[FIX] don't expect key 'host' to exist
Merge pull request #109 from mariuszmizgier/patch-1

[FIX] SQL query results in invalid reference